A NEW wheat variety with earlier sowing times will be needed if WA growers are to get the best out of their autumn rains.

Department of Agriculture and Food (DAFWA) wheat agronomy research officer Brenda Shackley is calling for a variety that sits in the maturing window between Mace and Whistler for optimum results across the Wheatbelt.

Ms Shackley outlined her reasoning at the Grains Research and Development Corporation (GRDC) Grains Research Updates last week, indicating optimising wheat yields across the whole farm was not necessarily achieved by sowing at the earliest opportunity.

She said risks from early sowing such as frost and disease could reduce yields by up to 1.5 tonnes per hectare.

"In our trials there was a yield penalty by going in too early in most varieties but once you get into May it evened out," she said.

"To maximise yield when pushing early you come to a lot of risks from frosts and disease and later you come to a risk from water deficit and high temperature."

Ms Shackley participated in DAFWA and GRDC-backed research in 2015 at Dandaragan, Katanning and Gibson which used three sowing dates in late-April, early-May and mid-May.

Some key findings were winter wheat varieties that are slower to mature may be more suited to early sowing in March or April when opportunities arise in WA, but more research is needed to find well adapted, high-yielding lines for local conditions.

"Most varieties obtained their highest yields at the early May sowing time or the yields were not significantly different between mid-April and early May sowings," she said.

"The exception was Whistler at Katanning, which obtained the highest yield sown mid-April."

Mace struggled to yield well at Dandaragan, it was hit by frost at Katanning and was down on all three sowing windows.

The 12 wheat lines evaluated at each site included: Mace as the benchmark; Whistler, which is a fast maturing winter variety that is showing some promise for WA conditions; and the newly released APW variety Cutlass which is showing similar maturity to Yitpi.

Across the trial sites, average grain yields ranged from more than 5.5t/ha for early May sowings at Dandaragan and Gibson to less than 2t/ha at Katanning for late May sowings.

Ms Shackley said highest yields were gained from early-May, and mid-April and early May sowings showed minimal difference in results.

Trials of sowing times, with a focus on variety results in early sowing, will continue in 2016.